From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C6FDC433F5 for ; Thu, 4 Nov 2021 20:22:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D968861053 for ; Thu, 4 Nov 2021 20:22:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232178AbhKDUZI (ORCPT ); Thu, 4 Nov 2021 16:25:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:23744 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229694AbhKDUZE (ORCPT ); Thu, 4 Nov 2021 16:25:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636057345; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=dyn4gVhrnOfU8Eh21VWnuvjYv16sLsfU5x56FULi4fI=; b=IHaFIR7wXvcxVxQLkmpgoQ3kSlhFDfSzwLB9RN1EY4YJ/WrOr1rJmD4g3KqUTnHeK+4mlr OeuwttDcFuiUvZVmZQzNFoTuB9bz/byUDuDazk12QLHr5kqntUEj91P/znBTnA/L3RtRZD rNNvDcNmNdrd+LqgnxCEBjntNchsDaA= Received: from mail-oi1-f199.google.com (mail-oi1-f199.google.com [209.85.167.199]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-435-02Wndk04OeOSzoAalsgJEA-1; Thu, 04 Nov 2021 16:22:24 -0400 X-MC-Unique: 02Wndk04OeOSzoAalsgJEA-1 Received: by mail-oi1-f199.google.com with SMTP id w123-20020aca3081000000b002a7aee8ee98so4090043oiw.21 for ; Thu, 04 Nov 2021 13:22:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=dyn4gVhrnOfU8Eh21VWnuvjYv16sLsfU5x56FULi4fI=; b=tenswQktIEuY6Tq6tbLMRQe/Aers7ffjyL/8RU76tjii4z8zUSA1Y5KUA51ifPgdVg xUFWvOkmgOxVL9VrZDUCn6tvHQuG4RIBP/TREk1VbpvuHskwgvd83OPtNUxlNN4wK+it xPly32LyHBWazo1RBDFd+7UQq3gsLpTSw0kKtGsa8NtkDHFSyOgZBALcC5iKlF16C7o7 71jh0pHTW0c9eUuCbN+6VzpJS1ILzVjJUTcBVvJOs0Gmf8wUjA+jVAdtzedBvGUSR6Dg lI/rO3WokVJ8frXSIGD1lu59JG5cp75dXGCGepF8DfsYELzrX8dU3kMsTHsXZwSiD2ey GXEQ== X-Gm-Message-State: AOAM533TpqTnNhi0lZwuQ6TsWfPaa5xvdpgJ8YGcHWGJc5ooqAPSwLE2 mvAOTT0ysqgG8JwZx5j4b0dcgrfTE7vaBL1D6kzn32njv/6SH0chO1dfKC3xosiM7NNNb5qIq6R WxrbWSkvi07ZFjkglJd2I3hO3 X-Received: by 2002:a9d:e8b:: with SMTP id 11mr17249540otj.43.1636057343772; Thu, 04 Nov 2021 13:22:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzBkcxVmtqTEAgJgg7bZE1R+nVxqWe50yOYbfV2om/neT0eXbjz5Z7sLZCcGedAO+B0IhBhxw== X-Received: by 2002:a9d:e8b:: with SMTP id 11mr17249524otj.43.1636057343540; Thu, 04 Nov 2021 13:22:23 -0700 (PDT) Received: from treble ([2600:1700:6e32:6c00::35]) by smtp.gmail.com with ESMTPSA id p62sm1714064oif.43.2021.11.04.13.22.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Nov 2021 13:22:23 -0700 (PDT) Date: Thu, 4 Nov 2021 13:22:20 -0700 From: Josh Poimboeuf To: Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, dvyukov@google.com, seanjc@google.com, pbonzini@redhat.com, mbenes@suse.cz Subject: Re: [RFC][PATCH 02/22] x86,mmx_32: Remove .fixup usage Message-ID: <20211104202220.xwm23nbpvwma6wds@treble> References: <20211104164729.226550532@infradead.org> <20211104165524.625383149@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20211104165524.625383149@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 04, 2021 at 05:47:31PM +0100, Peter Zijlstra wrote: > This code puts an exception table entry on the "PREFIX" instruction to > overwrite it with a jmp.d8 when it triggers an exception. Except of > course, our code is no longer writable, also SMP. > > Replace it with ALTERNATIVE, the novel > > XXX: arguably we should just delete this code > > Signed-off-by: Peter Zijlstra (Intel) > --- > arch/x86/lib/mmx_32.c | 83 ++++++++++++++++---------------------------------- > 1 file changed, 27 insertions(+), 56 deletions(-) > > --- a/arch/x86/lib/mmx_32.c > +++ b/arch/x86/lib/mmx_32.c > @@ -50,23 +50,17 @@ void *_mmx_memcpy(void *to, const void * > kernel_fpu_begin_mask(KFPU_387); > > __asm__ __volatile__ ( > - "1: prefetch (%0)\n" /* This set is 28 bytes */ > - " prefetch 64(%0)\n" > - " prefetch 128(%0)\n" > - " prefetch 192(%0)\n" > - " prefetch 256(%0)\n" > - "2: \n" > - ".section .fixup, \"ax\"\n" > - "3: movw $0x1AEB, 1b\n" /* jmp on 26 bytes */ > - " jmp 2b\n" > - ".previous\n" > - _ASM_EXTABLE(1b, 3b) > - : : "r" (from)); > + ALTERNATIVE "", > + "prefetch (%0)\n" > + "prefetch 64(%0)\n" > + "prefetch 128(%0)\n" > + "prefetch 192(%0)\n" > + "prefetch 256(%0)\n", X86_FEATURE_3DNOW I think this should instead be X86_FEATURE_3DNOWPREFETCH (which isn't 3DNow-specific and should really just be called X86_FEATURE_PREFETCH anyway) > + : : "r" (from)); > > for ( ; i > 5; i--) { > __asm__ __volatile__ ( > - "1: prefetch 320(%0)\n" > - "2: movq (%0), %%mm0\n" > + " movq (%0), %%mm0\n" Not sure why this prefetch was removed? It can also be behind an alternative just like the first one. -- Josh